The technical field relates to pedometers and more particularly to a pedometer that can measure the distance a user walks or runs by accurately measuring the stride the user takes.
Pedometers have been in use for many years and most indirectly measure the distance traveled by the user by counting the number of steps taken. The user preprograms a stride distance into the device and then by calculating the number of strides taken multiplied by the predetermined stride length, a distance is recorded by the pedometer. Such pedometers have a drawback, however, in that during the course of a run or walk, the user may not take a stride which is equal to the preset stride distance. Accordingly, only a rough approximation of the distance traveled can be made by these pedometers.
In addition, prior art pedometers also rely on a number of techniques to count the number of steps taken by the user. Most of these techniques rely on a change in acceleration each time a user""s foot contacts the ground. These changes are detected by a number of different acceleration sensitive devices. All of these devices rely on mechanical means to both count the number of steps or strides taken and to determine the distance of each stride.
These prior art pedometers have limitations which result in inaccurate data. For example, using the assumption that a stride length is constant results in errors in distance measurement because actual stride length may vary considerably as a function of the terrain traversed and the speed at which the user is traveling.
Further, the use of mechanical devices for sensing and counting steps is unreliable under the varied conditions of running, jogging and walking.
In one embodiment an electronic pedometer is used to measure the stride length of a user. The pedometer has a first unit associated with one foot of the user including a pressure sensitive switch and a sound wave generator. The pedometer also includes a second unit associated with the second foot of the user including a pressure sensitive switch and a sound wave receiver. A processor is used to process sensed signals from each of the pressure sensitive switches and the sound wave generator. The processor is programmed to count each activation of the pressure sensitive switches and determines a point of maximum signal strength received from the sound wave generator. The processor also calculates the distance between the point of sensed maximum signal strength and the sound wave receiver, and the distance between activation of the pressure sensitive switch of the first unit and the last activation of the pressure sensitive switch of the second unit. The measurements calculated by the processor are used to calculate the stride length of the user.
In another embodiment a system is used to determine a distance traveled. The system uses an emitter for emitting a signal associated with one foot of the user and a signal sensor associated with the second foot of the user for receiving the emitted signal. The system also uses a processor for processing signals and calculating the stride length of the user.